image processing lambda

lambdas/imageProcessor/imageProcessor.js

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+const sharp = require("sharp");
+const exifReader = require("exif-reader");
+const { logger } = require("../shared");
+
+/**
+ * Extract metadata from an image buffer
+ * @param {Buffer} buffer - Image buffer
+ * @returns {Object} Extracted metadata
+ */
+async function extractMetadata(buffer) {
+  const image = sharp(buffer);
+  const metadata = await image.metadata();
+
+  let exifData = {};
+  if (metadata.exif) {
+    try {
+      exifData = exifReader(metadata.exif);
+    } catch (e) {
+      // EXIF parsing failed, continue without it
+      logger.warn("Failed to parse EXIF data", { error: e.message });
+    }
+  }
+
+  return {
+    // GPS data
+    latitude: parseGpsCoordinate(
+      exifData?.gps?.GPSLatitude,
+      exifData?.gps?.GPSLatitudeRef
+    ),
+    longitude: parseGpsCoordinate(
+      exifData?.gps?.GPSLongitude,
+      exifData?.gps?.GPSLongitudeRef
+    ),
+
+    // Camera info
+    cameraMake: exifData?.image?.Make || null,
+    cameraModel: exifData?.image?.Model || null,
+    cameraSoftware: exifData?.image?.Software || null,
+
+    // Date/time
+    dateTaken: parseExifDate(
+      exifData?.exif?.DateTimeOriginal || exifData?.image?.DateTime
+    ),
+
+    // Dimensions
+    width: metadata.width,
+    height: metadata.height,
+    orientation: metadata.orientation || 1,
+
+    // File info
+    fileSize: buffer.length,
+  };
+}
+
+/**
+ * Strip all metadata from an image buffer
+ * Uses sharp's rotate() which auto-orients AND strips EXIF
+ * @param {Buffer} buffer - Image buffer
+ * @param {string} format - Output format (default: 'jpeg')
+ * @returns {Buffer} Processed image buffer
+ */
+async function stripMetadata(buffer, format = "jpeg") {
+  const image = sharp(buffer);
+  const metadata = await image.metadata();
+
+  // Handle different formats
+  let processed;
+  if (metadata.format === "gif") {
+    // For GIFs, try to preserve animation but strip metadata
+    processed = await image
+      .gif()
+      .toBuffer();
+  } else if (metadata.format === "png") {
+    // For PNGs, rotate strips metadata and we output as PNG
+    processed = await image
+      .rotate() // Auto-orient and strip EXIF
+      .png()
+      .toBuffer();
+  } else if (metadata.format === "webp") {
+    processed = await image
+      .rotate()
+      .webp()
+      .toBuffer();
+  } else {
+    // Default to JPEG for best compatibility
+    processed = await image
+      .rotate() // Auto-orient and strip EXIF
+      .jpeg({ quality: 90 })
+      .toBuffer();
+  }
+
+  return processed;
+}
+
+/**
+ * Convert GPS DMS (degrees, minutes, seconds) to decimal
+ * @param {Array} dms - [degrees, minutes, seconds]
+ * @param {string} ref - N/S/E/W reference
+ * @returns {number|null} Decimal coordinate
+ */
+function parseGpsCoordinate(dms, ref) {
+  if (!dms || !Array.isArray(dms) || dms.length !== 3) {
+    return null;
+  }
+
+  const [degrees, minutes, seconds] = dms;
+  let decimal = degrees + minutes / 60 + seconds / 3600;
+
+  // South and West are negative
+  if (ref === "S" || ref === "W") {
+    decimal = -decimal;
+  }
+
+  // Round to 8 decimal places (about 1mm precision)
+  return Math.round(decimal * 100000000) / 100000000;
+}
+
+/**
+ * Parse EXIF date string to ISO date
+ * EXIF format: "YYYY:MM:DD HH:MM:SS"
+ * @param {string|Date} dateStr - EXIF date string or Date object
+ * @returns {Date|null} Parsed date
+ */
+function parseExifDate(dateStr) {
+  if (!dateStr) {
+    return null;
+  }
+
+  // If already a Date object
+  if (dateStr instanceof Date) {
+    return dateStr;
+  }
+
+  // EXIF format: "YYYY:MM:DD HH:MM:SS"
+  const match = String(dateStr).match(
+    /(\d{4}):(\d{2}):(\d{2}) (\d{2}):(\d{2}):(\d{2})/
+  );
+  if (match) {
+    const [, year, month, day, hour, minute, second] = match;
+    return new Date(`${year}-${month}-${day}T${hour}:${minute}:${second}`);
+  }
+
+  // Try parsing as ISO date
+  const date = new Date(dateStr);
+  return isNaN(date.getTime()) ? null : date;
+}
+
+/**
+ * Get the MIME type for a format
+ * @param {string} format - Image format
+ * @returns {string} MIME type
+ */
+function getMimeType(format) {
+  const mimeTypes = {
+    jpeg: "image/jpeg",
+    jpg: "image/jpeg",
+    png: "image/png",
+    gif: "image/gif",
+    webp: "image/webp",
+  };
+  return mimeTypes[format] || "image/jpeg";
+}
+
+module.exports = {
+  extractMetadata,
+  stripMetadata,
+  parseGpsCoordinate,
+  parseExifDate,
+  getMimeType,
+};